P2P for Mobile Providers

ABSTRACT

Methods and arrangements for arranging a distribution tree in a Peer To Peer P2P streaming system are included. The system includes a bootstrapping server that creates an external distribution tree based on received register messages from participating operator external clients. The method includes configuring an operator controlled node to be a regular node in the created external distribution tree. The method includes configuring the operator controlled node to be a parent node for participating operator internal clients.

TECHNICAL FIELD

The present invention generally relates to systems and methods and, moreparticularly, to mechanisms and techniques for arranging a distributiontree in a Peer to Peer P2P streaming system.

BACKGROUND

P2P streaming applications are becoming commonplace on the PC and itforeseen that they will make their way into networked ConsumerElectronic CE devices (e.g. MP3 players, media players etc). P2Pstreaming applications will also be available on mobile phone devices.Examples of P2P streaming applications are Joost (video) and Spotify(music).

P2P streaming applications work in much the same way as other P2Pfileshare clients except that instead of downloading files, the usersdownload streams. These streams are then exchanged in real-time withother users. Depending on implementation, no data might be storedlocally on any machine connected to the network.

In these applications, an overlay construction mechanism organizesparticipating peers into multiple trees. Each peer determines a propernumber of trees to join based an its access link bandwidth. To minimizethe effect of churn and effectively utilize available resources in thesystem, participating peers are organized into multiple diverse trees.With diverse trees, each peer is placed as an internal node in only onetree and leaf node in other participating trees. When a peer joins thesystem, it contacts a bootstrapping server to identify a parent node inthe desired number of trees. To keep the population of internal nodesbalanced among different trees, a new node is added as an internal nodeto the tree that has the minimum number of internal nodes. An example ofmultiple diverse trees can be seen below:

P2P streaming applications are built on either tree-based or meshedbased architectures. They differ in the way the peers relate to oneanother. Specifically in tree based systems the relationship betweenparent peers and child peers are static and a rigid tree structure ismaintained during the system run time. In mesh-based there is no welldefined relationship between parent and child peers, participating peersform a randomly connected overlay, or a mesh. In mesh-based systems eachpeer tries to maintain a certain number of parents (i.e., incomingdegree) and also serves a specific number of child peers (i.e., outgoingdegree). Upon arrival, a peer contacts a bootstrapping server to receivea set of peers that can potentially serve as parents. The bootstrappingserver maintains the outgoing degree of all participating peers.Individual peers periodically report their newly available packets totheir child peers and request specific packets from individual parentpeers. A parent peer periodically receives an ordered list of requestedpackets from each child peer, and delivers the packets in the requestedorder. The requested packets from individual parents are determined by apacket scheduling algorithm at each child peer.

With time, when the business models have been worked out, P2P streamingapplications will offer both audio and video. PCs (e.g. laptops) andsome Consumer Electronic CE devices can today be connected to thecellular network e.g. via HSPA USB dongles. The behavior of end usershas been shown not to change as they switch one access technology toanother; hence traffic trends persist to a large extent as users switchfrom fixed to wireless accesses. It is then very logical to concludethat PCs, CEs and mobile devices will use the cellular network (3G/4G)to run P2P streaming applications in the near future. FIG. 1 a showssegments of a 3GPP architecture impacted by P2P traffic. FIG. 1 adiscloses clients/laptops 2,3,4 within an internet network andclients/laptops 1,5,6 that communicate via Radio Base Stations RBSswithin a radio access network that is part of a core network. Thearchitecture of 3GPP mobile networks is built around tunneling. Thetunnels are shown in FIG. 1 a with dotted lines. In FIG. 1 a a signalinggateway 15 acts as a tunnel terminating node and a packet Data NetworkGateWay 20 is the tunnel ingress/egress point for all internet traffic.All traffic from/to the radio based laptops 1,5,6 will go through 20.FIG. 1 b discloses a tree structure according to prior art. In thissimplified example content will be streamed S1, S2, S3, S4, S5 from theroot of the tree i.e. node 2 in this example, downwards to all nodes inthe tree. As can be seen in FIG. 1 a traffic will negatively impact theradio access network and the core network. Due to the construction ofthe tree, content from node 6 to node 1 will be streamed S5 via thesignaling gateway 15 and consequently causes extra load to the network.Furthermore, a requirement imposed by P2P systems on operators is thatall nodes participating in the P2P system must contribute with theiruplink capacity to the P2P network. This will also negatively impact theradio access network and the core network.

SUMMARY

An object of the invention is to overcome above identified limitationsof the prior art. The invention focuses on the construction of adistribution tree of a P2P streaming systems so that negative impact onradio and core network will be reduced.

The basic concept of the invention is introduction of an operatorcontrolled peer to act as parent peer for all operator internal clients.

The solution to the problems more in detail is a method for arranging adistribution tree in a Peer to Peer P2P streaming system. The systemcomprises a bootstrapping server that creates an external tree uponreception of register messages from participating operator externalclients. The method further comprises the following steps:

-   -   An operator controlled node is configured to be a regular node        in the created external distribution tree.    -   The operator controlled node is configured to be a parent node        for participating operator internal clients.

According to one exemplary embodiment, a method and arrangement forarranging a distribution tree with a static tree structure is disclosed.Register messages from participating operator internal clients arecaptured by the operator controlled node, which messages are intendedfor the bootstrapping server. Replies that imitate the bootstrappingserver are sent to the internal clients, which replies decide theoperator controlled node as parent node for the internal clients. Thetree is hereby arranged in a way that operator internal clients areconcealed behind the operator controlled node so that dictated treeformation rules do not apply for the internal clients and their radiouplink capacity is hence spared.

According to another exemplary embodiment, an operator controlled nodeaccording to the invention is disclosed. The node is configurable towork in two modes: peer and parent mode. In the peer mode the node isable to join an external network where it appears as regular peer. Forinternal peers inside an operator's network, the node works in theparent mode.

According to yet another exemplary embodiment, streaming of content in adistribution tree arranged according to the invention has beendisclosed.

An object of the invention is to reduce negative traffic impact on theradio access network and the core network. This object and others areachieved by methods, arrangements, nodes, systems and articles ofmanufacture.

Advantages of the invention are the reduced negative traffic impact onthe radio access network and the core network (especially where theoperator pays for transit traffic). Besides, the traffic over the radioaccess as well as the System Architecture Evolution SAE core networkwill be reduced as a result of eliminating the P2P uplink usage ofinternal peers. This is especially important as the radio access is avery scare resource. Also depending on the business model the operatorbenefits by the reducing of the amount of bits transported over the SAEcore network. This is especially relevant in countries where theoperator has a legal requirement to rent (rather than own) the SAE coretransport from third party providers.

The invention will now be described more in detail with the aid ofpreferred embodiments in connection with the enclosed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic illustration according to prior art of acommunication system comprising a plurality of clients connected to acore network via a mobile access network, and clients connected to aninternet network. A packet data network gateway is the tunnelingress/egress point for all internet traffic.

FIG. 1 b discloses a tree structure according to prior art.

FIG. 2 a is a schematic illustration of a communication systemcomprising a plurality of clients connected to a core network via amobile access network and clients connected to an internet network. Apacket data network gateway is the tunnel ingress/egress point for allinternet traffic and an operator controlled node is arranged as part ofthe packet data network gateway.

FIG. 2 b discloses a tree structure according to the invention.

FIG. 3 discloses a signal sequence diagram representing a method forarranging a distribution tree in a Peer To Peer P2P streaming system.

FIG. 4 discloses a block schematic illustration of an operatorcontrolled node.

FIG. 5 discloses a signal sequence diagram representing streaming ofcontent in a tree structure created according to the invention.

DETAILED DESCRIPTION

FIG. 2 a discloses an exemplary embodiment of the invention. The figureshows a peer to peer P2P network that includes plural peers/clients 1-6(laptops in this example). The laptops 2,3,4 are connected via accessnetworks (not shown in the figure) to an internet network, and laptops1,5,6 are connected via a mobile access network to a Core Network. Thefigure discloses a very simplified example and the number of clients arein the reality much higher. The clients may be, for example, a mobilephone, a computer, a set top box, or other devices that are capable ofexchanging information with the internet, i.e. even though connected viaa mobile access, also the clients 1,5,6 can be either wireline orwireless clients. The access networks connecting the laptops 2,3,4 canbe for example a communication network, a phone network, an internetservice provider, etc.

The mobile network and the core network together constitutes a 3^(rd)Generation Partnership Project (3GPP) mobile network. The architectureof 3GPP mobile networks is built around tunneling. In this network, theclients 1,5,6 each are given an IP address that does not change and istopologically anchored in a signaling gateway 15, regardless of wherethe client device actually is located in the IP domain. The signalinggateway 15 acts as a tunnel terminating node. The tunnels are shown inFIG. 2 a with dotted lines. A packet Data Network GateWay 20 is thetunnel ingress/egress point for all internet traffic and all trafficfrom/to the radio based laptops 1,5,6 will go through the gateway 20.Downloaded streams S1, S6 and S7 can be seen in FIG. 2 a. These streamswill be further explained later in the description. A P2P control nodePCN 7 is in this example part of the packet Data Network GateWay 20. ThePCN is a vital part of the invention and will be further explainedtogether with for example FIG. 4. A bootstrapping server BSTR 10 islocated within the Internet. The bootstrapping server functions as adirectory service for clients participating in the P2P network. Thebootstrapping server is responsible for creating a distribution treebased on participating nodes.

FIG. 2 b discloses a distribution tree created according to theinvention. The tree comprises nodes/peers 1-7. The streams S1, S6 and S7that already have been mentioned in FIG. 2 a can also be seen in FIG. 2b. According to prior art, in P2P streaming applications for peers tobecome part of the P2P network they have to send register messages tothe bootstrapping server 10. The bootstrapping server would assign thenew peers a parent peer from a list of already existing peers and in sodoing will create a new branch of the P2P distribution tree. A reply issent back to the new peers indicating the parent peer. Upon getting thereply, the new peers become part of a tree in the P2P network and maystart sending content requests to the parent peer. An operatorcontrolled peer PCN 7 is according to the invention implemented byincluding a set of new P2P-aware functionalities collectively called P2Pcontrol node 7 into a node where GTP tunnels are terminated. Theterminating node is the PDN gateway 20 in this example. The significanceof placing the PCN into the PDN GW 20 is that it is the ingress/egresspoint for all internet traffic; hence all the traffic from/to the mobilepeers will go through it and this is important as the PCN node will bein the signaling path of the P2P traffic.

The method according to the first embodiment will now be explainedtogether with FIG. 3. FIG. 3 is a signal sequence diagram wherein thesignalling points i.e. the laptops 1-6, the operator controlled node 7and the bootstrapping server 10 that were explained earlier togetherwith FIG. 2 a have been disclosed. The method will show the arranging ofa distribution tree according to the invention. The method comprises thefollowing steps:

-   -   The method starts by creating a tree that comprises the nodes 2,        3 and 4. According to well known technique in P2P streaming        applications, for clients to become part of the P2P network they        have to send register messages to the bootstrapping server 10.        The bootstrapping server would assign the new clients a parent        peer from a list of already existing clients and in so doing        will create a new branch of the P2P distribution tree. A reply        is sent back to the new client indicating the parent peer. Upon        getting the reply, the new peers become part of the tree. In        FIG. 3 this has been performed by the clients 2, 3 and 4 by        sending the register messages 31, 33 and 35 and receiving the        replies 32, 34 and 36. The tree now comprises the nodes 2, 3 and        4 (see also FIG. 2 b). So far the tree has been created        according to prior art.    -   According to the invention, the operator controlled peer is        implemented by including a set of new P2P-aware functionalities        collectively called P2P control node PCN 7 as part of the PDN        gateway 20. As will be seen, the P2P control node PCN 7 will        logically separate the internal peers from the external peers in        the Internet.    -   The operator controlled peer 7 sends a request 37 for a root        node to the bootstrapping server 10.    -   The bootstrapping server 10 replies 38 with parent node        information, this is usually a list of nodes which can serve as        parent for the operator controlled peer 7. In this example the        nodes 3 and 4 are suggested as parents (see FIG. 2 b).    -   The operator controlled peer 7 selects node 4 to be parent node        and registers 39 to node 4 as child node. From here on, the        operator controlled node 7 and node 4 can exchange content        chunks.    -   The mobile peer 1 sends a register message 40 addressed to the        bootstrapping server 10, requesting to get the address of its        parent server. This message serves to inform the bootstrapping        server that a new peer is joining the P2P network.    -   The operator controlled node 7 captures 41 according to the        invention the message 40 with the aid of Deep Packet Inspection        DPI. The message 40 is suppressed 41 by the node 7 and is not        propagated to the bootstrapping server.    -   A bootstrapping server reply message 43 is re-created 42 by the        operator controlled node 7.    -   The message 43 is sent back from 7 to the mobile peer 1 as        though from the boot strapping server with 7 as the parent peer        i.e. the reply 43 is sent to the mobile peer 1 from 7 that        imitates the bootstrapping server 10. The reply decides the        operator controlled node 7 as parent node for the internal        clients. So far the following nodes have been created in the        distribution tree: 2, 3, 4, 7 and 1 (see FIG. 2 b). Logically        the PCN 7 is now the parent to the mobile peer 1 and for this        reason it receives all the requests for content from the mobile        peer. Being a parent peer, the PCN will also be the P2P node        which acts as the source of content for the internal mobile        peers. The significance of placing the PCN into the PDN GW is        that it is the ingress/egress point for all internet traffic;        hence all the traffic from/to the internal clients will go        through it and this is important as the PCN node will be in the        signalling path of the P2P traffic.    -   In the same way as described above, a message 44 from the mobile        peer 5 is received and suppressed 45 by 7 and a reply message 47        is re-created 46 and sent back to the mobile peer 5. The        following nodes have now been created in the distribution tree:        2, 3, 4, 7, 1 and 5.    -   In the same way as earlier described, a message 48 from the        mobile peer 6 is received and suppressed 49 by 7 and a reply        message 51 is re-created 50 and sent back to the mobile peer 6.        The following nodes have now been created in the distribution        tree: 2, 3, 4, 7, 1, 5 and 6.

When comparing the tree created according to prior art (FIG. 1 b) withthe tree created according to the invention (FIG. 2 b) it can be seenthat all the internal mobile peers now have been concealed behind theoperator controlled node. The significance of this is that the operatorcan remove the requirement imposed by P2P systems that all peers mustcontribute with their uplink capacity to the P2P network. Hence with thePCN in place the mobile peers are concealed behind the PCN and will beable to get content from the P2P network without contributing in return.The PCN will do all the contribution on behalf of the mobile peers, thisway satisfying the requirement of the P2P network and at the same timereducing bandwidth utilization inside the mobile network.

The described concept also applies to pre-SAE architecture in which casethe PCN could be hosted by the GGSN.

The above described example covers mesh based or pull-based P2P. Thereis another type of P2P streaming and that is the ‘tree-based’ or pushbased P2P. Here the peers do not ask the parent node for a chunk, theyonly get what the parent gives them. In a mesh based system there aretwo main types of requests from a peer; bootstrapping request and chunkrequest, the chunk request will be further clarified together with FIG.5 in this application. In a tree-based or push-based, here after gettinga parent the child peers only receives whatever the parent node gives it(very much like the way multicast works). The peer only makes abootstrapping request. There is yet a third approach called hybrid, heredepending on the specific implementation the idea is to combine featuresof mesh and tree based approaches. The invention covers all threeapproaches. This will be obvious to someone skilled in the art.

FIG. 4 discloses the structure of the operator controlled PCN node 7.The PCN is a collection of functions which enable the operator tocontrol the traffic of P2P streaming applications by influencing how theP2P distribution tree is built. The main component is the Deep PacketInspection DPI module 21 which enables to identify P2P control messagessent by the mobile peers. Deep Packet Inspection is a form of computernetwork packet filtering that examines the data and/or header part of apacket as it passes an inspection point to decide if the packet can passor if it needs to be routed to a different destination. When a newmobile peer sends a message to the bootstrapping server requesting toget the address of its parent server, the PCN functionality captures themessage with the aid of DPI. The mobile peer's message is not propagatedto the bootstrapping server. Instead a bootstrapping server replymessage is re-created by the Message Processing Logic 24 in the PCN. TheMessage Processing Logic 24 is also responsible for modifying receivedrequests to simulate that the PCN is requesting content chunk. This willbe further discussed together with FIG. 5. The P2P client 22 in the PCNfunctions in two modes; peer and parent mode. In the peer mode the PCNis able to join external P2P network where it appears as a regular peer.For the internal mobile peers inside the operator's network, the PCNworks in the parent mode. The P2P client 22 also selects a node ofsuggested nodes as parent node, as described in the first embodiment.The P2P Content Storage 23 is responsible for cashing streamed contentthat passes the PCN, this will be further clarified when FIG. 5 isexplained. Furthermore, the PCN comprises means for sending re-createdreplies to peers that imitates the bootstrapping server, and means forsending requests (e.g. for a parent node or for content chunky and meansfor sending content chunk, and means for receiving replies (e.g. nodesuggestions or requests for content chunk) and means for receivingcontent chunk. The above mentioned send and receive means are not shownin FIG. 4 in an attempt to make the figure more clear andunderstandable.

FIG. 5 is a signal sequence diagram wherein the signalling points i.e.the clients/laptops 1-6 and the operator controlled node 7 that wereexplained earlier together with FIG. 2 a have been disclosed. Apre-requisite for the method below is that the distribution tree shownin FIG. 2 b has been arranged. The method is to be seen as acontinuation of the method shown in FIG. 3. The method will show therequesting for content by the clients 1,5,6, and streaming of therequested content. The well known principle behind streaming is that aparent peer gets requests for content chunk from child peers and supplythe child peers with the chunk if it is in their possession. If it isnot, a request is made further to the parent peers of the parent nodeand so on till a peer supplies the chunk.

The streaming method according to the invention comprises the followingsteps:

-   -   The internal peer 1 sends a request 60 to its parent for content        chunk. Since the distribution tree has been created according to        the invention, the parent for peer 1 is the operator controlled        node PCN 7.    -   With the aid of Deep Packet Inspection DPI 21 (see FIG. 4), the        message is identified 61 as a message sent by an internal peer.    -   The operator controlled node is not in possession of the        requested chunk and the chunk must therefore be further        requested from the parent's 7 parent i.e. node 4 in this case.        The received request 60 is modified 61 according to the        invention in the Message Processing logic 24 (see FIG. 4) in the        operator controlled node 7 to simulate that the operator        controlled node is requesting the content chunk from 4. This is        because for the external peers 2,3,4 the internal peers 1,5,6 do        not exist as only the operator controlled node 7 is part of the        external tree.    -   The modified request simulating that the operator controlled        node 7 is requesting the content chunk is sent 62 from the        operator controlled node to the external peer 4.    -   The external peer 4 is in possession of the content chunk and        streaming S6 takes place from peer 4 to the operator controlled        node 7.    -   The streamed content is cached CACHE in the P2P content storage        23 (see FIG. 4).    -   Streaming S7-1 of the content now takes place from the operator        controlled node 7 to the internal peer 1.    -   FIG. 5 further discloses how the internal peers 5, 6 request 63,        65 the same content chunk as was requested by 1. The content        chunk is fetched 64, 66 from the P2P content storage 23 and        streamed S7-2 and S7-3 from the operator controlled node 7 to 5        and 6 respectively. The benefit with the cashing is that the        latency of accessing popular content will be reduced as it is        now served from the cache of the operator controlled node.

A system that can be used to put the invention into practice isschematically shown in the FIG. 2 and FIG. 4. Enumerated items are shownin the figures as individual elements. In actual implementations of theinvention, however, they may be inseparable components of otherelectronic devices such as a digital computer. Thus, actions describedabove may be implemented in software that may be embodied in an articleof manufacture that includes a program storage medium. The programstorage medium includes data signals embodied in one or more of acarrier wave, a computer disk (magnetic, or optical (e.g., CD or DVD, orboth), non-volatile memory, tape, a system memory, and a computer harddrive.

The systems and methods of the present invention may be implemented forexample on any of the Third Generation Partnership Project (3GPP),European Telecommunications Standards Institute (ETSI), AmericanNational Standards Institute (ANSI) or other standard telecommunicationnetwork architecture. Other examples are the Institute of Electrical andElectronics Engineers (IEEE) or The Internet Engineering Task Force(IETF).

The description, for purposes of explanation and not limitation, setsforth specific details, such as particular components, electroniccircuitry, techniques, etc., in order to provide an understanding of thepresent invention. But it will be apparent to one skilled in the artthat the present invention may be practiced in other embodiments thatdepart from these specific details. In other instances, detaileddescriptions of well-known methods, devices, and techniques, etc., areomitted so as not to obscure the description with unnecessary detail.Individual function blocks are shown in one or more figures. Thoseskilled in the art will appreciate that functions may be implementedusing discrete components or multi-function hardware. Processingfunctions may be implemented using a programmed microprocessor orgeneral-purpose computer. The invention is not limited to the abovedescribed and in the drawings shown embodiments but can be modifiedwithin the scope of the enclosed claims.

1. Method for arranging a distribution tree in a Peer To Peer (P2P)streaming system comprising a bootstrapping server that creates anexternal distribution tree based on received register messages fromparticipating operator external clients, the method comprising thefollowing steps: configuring an operator controlled node to be a regularnode in the created external distribution tree; and configuring theoperator controlled node to be a parent node for participating operatorinternal clients.
 2. Method for arranging a distribution tree in a PeerTo Peer (P2P) streaming system according to claim 1, further comprisingthe following steps: capturing register messages from the participatinginternal clients by the operator controlled node, which messages areintended for the bootstrapping server; re-creating captured registermessages; and replying to the internal clients with a reply thatimitates the bootstrapping server, which reply decides the operatorcontrolled node as parent node for the internal clients.
 3. Method forarranging a distribution tree in a Peer To Peer streaming systemaccording to claim 2, further comprising the following further steps:preventing the captured register messages from reaching thebootstrapping server.
 4. Method for arranging a distribution tree in aPeer To Peer streaming system according to claim 1, wherein theconfiguring of the operator controlled node to be a node in the externaltree comprises the following further steps: sending a request for aparent node, from the operator controlled node to the bootstrappingserver; sending node suggestions amongst nodes in the created externaldistribution tree, from the bootstrapping server to the operatorcontrolled node; and selecting at least one node of the suggested nodesas parent node(s) for the operator controlled node.
 5. Method forarranging a distribution tree in a Peer To Peer streaming systemaccording to claim 2, further comprising the following steps: sending arequest for content chunk from an internal client to the operatorcontrolled node; modifying the received request in the operatorcontrolled node to simulate that the operator controlled node isrequesting the content chunk; sending the modified request from theoperator controlled node to an external client.
 6. Method for arranginga distribution tree in a Peer To Peer streaming system according toclaim 5, further comprising the following steps: sending the requestedcontent chunk from the external client to the operator controlled node;forwarding the received content chunk from the operator controlled nodeto the internal client.
 7. Method for arranging a distribution tree in aPeer To Peer P2P streaming system according to claim 6, furthercomprising the following steps: storing the received content chunk. 8.Method for arranging a distribution tree in a Peer To Peer P2P streamingsystem according to claim 7, further comprising the following steps:receiving from a second internal client to the operator controlled node,a request for the content chunk; delivering the stored content chunk tothe second internal client.
 9. Method for arranging a distribution treein a Peer To Peer P2P streaming system according to claim 1, furthercomprising performing the steps on at least one of tree-based andhybrid-based P2P systems.
 10. Method for arranging a distribution treein a Peer To Peer P2P streaming system according to claim 1, furthercomprising performing connectivity between the internal clients usingtunnelling.
 11. An operator controlled node for arranging a distributiontree in a Peer To Peer P2P streaming system, wherein the node comprises:electronics that configure the node to be a regular node in an operatorexternal distribution tree; electronics that configure the node to be aparent node for participating operator internal clients.
 12. An operatorcontrolled node for arranging a distribution tree in a Peer To Peer P2Pstreaming system according to claim 11, which node further comprises:electronics for performing deep packet inspection for identification ofreceived messages sent by operator internal clients.
 13. An operatorcontrolled node for arranging a distribution tree in a Peer To Peer P2Pstreaming system according to claim 11, which node further comprises:electronics for configuring the node to function in two modes, regularpeer mode and parent mode.
 14. An operator controlled node for arranginga distribution tree in a Peer To Peer (P2P) streaming system accordingto claim 11, which node further comprises: electronics for cashingreceived streamed content.
 15. An operator controlled node for arranginga distribution tree in a Peer To Peer P2P streaming system according toclaim 11, which node further comprises: electronics for re-creatingreceived messages.
 16. An arrangement for arranging a distribution treein a Peer To Peer (P2P) streaming system comprising a bootstrappingserver that creates an external distribution tree based on receivedregister messages from participating operator external clients, whicharrangement comprises: electronics for configuring an operatorcontrolled node to be a regular node in the created externaldistribution tree; electronics for configuring the operator controllednode to be a parent node for participating operator internal clients.17. An arrangement for arranging a distribution tree in a Peer To Peer(P2P) streaming system according to claim 16, which arrangement furthercomprises: electronics for capturing register messages from theparticipating internal clients by the operator controlled node, whichmessages are intended for the bootstrapping server; electronics forre-creating captured register messages; electronics for replying to theinternal clients with a reply that imitates the bootstrapping server,which reply decides the operator controlled node as parent node for theinternal clients.
 18. An arrangement for arranging a distribution treein a Peer To Peer streaming system according to claim 17, whicharrangement further comprises: electronics for preventing the capturedregister messages from reaching the bootstrapping server.
 19. Anarrangement for arranging a distribution tree in a Peer To Peerstreaming system according to claim 16, which arrangement furthercomprises: electronics for sending a request for a parent node, from theoperator controlled node to the bootstrapping server; electronics forsending node suggestions amongst nodes in the created externaldistribution tree, from the bootstrapping server to the operatorcontrolled node; electronics for selecting at least one node of thesuggested nodes as parent node(s) for the operator controlled node. 20.An arrangement for arranging a distribution tree in a Peer To Peerstreaming system according to claim 17, which arrangement furthercomprises: electronics for sending a request for content chunk from aninternal client to the operator controlled node; electronics formodifying the received request in the operator controlled node tosimulate that the operator controlled node is requesting the contentchunk; electronics for sending the modified request from the operatorcontrolled node to an external clients.
 21. An arrangement for arranginga distribution tree in a Peer To Peer streaming system according toclaim 20, which arrangement further comprises: electronics for sendingthe requested content chunk from the external client to the operatorcontrolled node; electronics for forwarding of the received contentchunk from the operator controlled node to the internal client.
 22. Anarrangement for arranging a distribution tree in a Peer To Peer P2Pstreaming system according to claim 21, which arrangement furthercomprises: electronics to store the received content chunk.
 23. Anarrangement for arranging a distribution tree in a Peer To Peer (P2P)streaming system according to claim 22, which arrangement furthercomprises: electronics configured to receive from a second internalclient to the operator controlled node, a request for the content chunk;electronics configured to deliver the stored content chunk to the secondinternal client.
 24. Article of manufacturing comprising a programstorage medium having a computer readable code embodied therein forarranging a distribution tree in a Peer To Peer P2P streaming system,which computer readable program code comprises: computer readableprogram code for configuring an operator controlled node to be a regularnode in a created external distribution tree; computer readable programcode for configuring the operator controlled node to be a parent nodefor participating operator internal clients.